Effect of Surface Treatment Process on Electrochemical Migration of Substrate Surface

Water drop tests were used to investigate the effect of three common surface treatment processes (organic solder mask, immersion tin, and electroless nickel gold) on electrochemical migration (ECM) of BT resin substrates, ceramic substrates, and FR-4 substrates. The results showed that the ECM mechanism of the samples with organic solder mask and immersion tin surface treatment accorded with the classical ECM model; the ECM of the samples with chemical nickel gold surface treatment process showed the growth of anodic susceptor. The solubility of nickel oxides and hydroxides formed in the solution was a key factor in the growth of the anodic lattice. The resistance of the three kinds of surface treatment to the electrochemical migration from strong to weak was:chemical nickel gold, organic solder mask and immersion tin. For the sample using the chemical nickel gold surface treatment process, the resistance of the ceramic substrate to the electrochemical migration was superior to that of the FR-4 substrate, and for the other two surface treatment processes, the resistance of the substrate to the ECM was consistent, from strong to weak were:BT resin substrate, ceramic substrate and FR-4 substrate.